Considerin the slow airspeed decay, a quick "check speed" would have likely been sufficient to prevent the situation from ever occuring.
As far as snoozing on the jumpseat, absolutely. I'd want them awake for taxi, takeoff, approach, and landing... once we get up into cruise...whatever. I'd rather have them alert when we're in a more critical environment.
I've found it quite difficult to snooze in the jumpseat unless i was really zonked. The conversation is typically more enjoyable with the 3rd person up front, too.